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• Allergic rhinitis

  • Also called hay fever
  • Triggered by pollinating plants
  • Type 1 hypersensitivity reaction
• Genetic and environmental factors contribute to the type of T-cell group, influencing the overall immune response
• Rhinitis

  Nasal inflammation
• Type 1 hypersensitivity reaction

  1. Starts with exposure to an environmental allergen

  2. Dendritic cell gobbles up the foreign particle and presents it to a T cell

  3. Activated T cell produces cytokines to involve other immune cells

  4. Imbalance in T cells leads to B cells producing IgE antibodies

  5. IgE antibodies bind to mast cells which release histamine upon re-exposure to allergen
• Skin prick test

  Small drops of allergens placed on the skin and pricked to check for allergic reactions like raised bumps or wheels
• Symptoms of allergic rhinitis include nasal congestion, red itchy swollen eyes, sneezing, affecting concentration, sleep, work, and school attendance
• Skin prick tests can have low sensitivity or specificity
• Nasal irrigation can reduce congestive symptoms of allergic rhinitis
• Antihistamines can be used to suppress mast cell degranulation effects
• Allergic rhinitis is a type 1 hypersensitivity reaction causing inflammation of eyes and nose due to airborne allergens
• Early exposure to allergens

  Might protect against type 1 hypersensitivity
• Desensitization

  Exposing the body to micro doses of allergen and gradually increasing to boost tolerance and reduce IgE production
• Allergic rhinitis

  Nasal inflammation caused by allergens like hay, pollen, dust, animal hair, or mold spores
• Diagnosis of allergic rhinitis is based on skin appearance and identifying allergic triggers
• Best approach for allergic rhinitis is to avoid triggering allergens
• Production of IgE antibodies in asthma is an example of a Type 1 hypersensitivity reaction
• Factors contributing to asthma

  • Genetic factors
  • Environmental factors
  • Hygiene hypothesis
• People with asthma can have asthma exacerbation or asthma attacks, usually triggered by something in the environment causing immune cells to generate inflammation in the lungs, potentially life-threatening
• Molecular pathway leading to asthma

  1. Often initiated by an environmental trigger

  2. Excessive reaction from type 2 helper cells or Th2 cells against specific allergens

  3. Th2 cells produce cytokines like IL-4 and IL-5 leading to features of asthma

  4. IL-4 leads to production of IgE antibodies which coat mast cells and stimulate release of granules containing histamines, leukotrienes, and prostaglandins

  5. IL-5 activates eosinophils which release more cytokines and leukotrienes
• Asthma

  Causes chronic inflammation of the airways, making them narrow and more difficult to breathe through
• Specific causes of asthma are ultimately unknown, thought to be caused by a combination of genetic and environmental factors
• Components of the lungs

  • Trachea
  • Right and left bronchi
  • Bronchioles
  • Lumen
  • Mucosa
  • Lamina propria
  • Submucosa
• asthma

  panting
• Events in asthma

  1. Minutes after exposure to allergen, smooth muscle around bronchioles spasm and there is increased mucus secretion

  2. Increase in vascular permeability and recruitment of additional immune cells from the blood

  3. A few hours after exposure, immune cells release chemical mediators damaging the endothelium of the lungs

  4. Inflammatory changes are initially reversible but over time lead to irreversible changes like edema, scarring, fibrosis, thickening of epithelial basement membrane reducing airway diameter
• Causes of childhood asthma diagnosed before age 12 are thought to have a stronger genetic influence, whereas later onset asthma is more likely due to environmental factors
• Causes of childhood asthma diagnosed before age 12


  Thought to be due to a stronger genetic influence
• Charcot-Leyden crystals

  • Shaped like needles and formed by the breakdown of eosinophils
• Symptoms of asthma

  • Coughing
  • Feeling of chest tightness
  • Dyspnea or difficulty breathing
  • Wheezing
• There is no cure for asthma
• Triggers of asthma exacerbations or attacks


  Start up more inflammation leading to smooth muscle spasms and mucus production, making it hard to breathe
• Types of asthma

  • Intermittent asthma
  • Mild persistent asthma
  • Moderate persistent asthma
  • Severe persistent asthma
• Common triggering substances for asthma attacks

  • Air pollution like cigarette smoke and car exhaust
  • Allergens like dust, pet dander, cockroaches, and mold
  • Medications like aspirin and beta-blockers
• Mucus plugs


  • Block exchange of air and inhaled medications from getting to the site of inflammation
• Asthma is characterized by chronic inflammation in the lungs and asthma exacerbations or attacks
• Occasional findings in sputum of people with bronchial asthma

  • Curschmann spirals
  • Charcot-Leyden crystals
• Classification of asthma

  1. Frequency of symptoms

  2. FEV1 and PEFR measurements

  3. Frequency of asthma medication usage
• Later onset asthma


  More likely to be largely due to environmental factors
• Treatments for asthma

  1. Avoid or minimize contact with triggering substances

  2. Vacuuming, removing carpets and rugs, changing environmental conditions

  3. Medications like bronchodilators, corticosteroids, long-acting beta-adrenoceptor agonists, leukotriene antagonists

  4. In severe cases, intravenous corticosteroids, magnesium sulfate, and oxygen therapy might be needed
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• Acid secreted by the stomach helps in food digestion